ASi-5 Safety

ASi-5 Safety launches input modules with safe and non-safe signals

ASi-5 Safety is now certified and ready for use and will optimally complement the established ASi Safety line in the future. The latest Safety generation can be easily integrated into existing solutions. Main advantage of ASi-5 Safety: You can use many safe and non-safe signals under just a single address

Discover now our first ASi-5 Safety input modules with 2 safe inputs each and up to 12 standard signals. For example, the ASi-5 Safety input modules allow you to connect an operating panel to ASi cost-effectively – with several illuminated pushbuttons, an E-stop button and a safe key switch.

The advantages of our first ASi-5 Safety input modules

Full Compatibility

ASi-5 Safety is compatible with all previous ASi devices and components and can be easily integrated into existing solutions.

Only one node Number

ASi-5 Safety allows many safe and non-safe signals to be used under just one address.

Reduced machine-related costs

The ASi-5 Safety module with 2 safe inputs are similarly priced to ASi-5 modules with just standard I/Os.


Bihl+Wiedemann has steadily expanded its safety technology solution portfolio since 2005. After a short overview of previous Safety highlights, product manager Paul Werge presents the first two ASi-5 Safety input modules in IP67: BWU4209 has 2 safe inputs for floating contacts, BWU4210 has 2 safe inputs for optoelectronic devices. Both modules additionally have 12 digital self-configuring I/Os each.


Video length: 1:54

Fig.: By combining standard and safety signals, many different applications can be achieved from the same module.  

FAQs about ASi-5 Safety

There are already many different safety controllers and solutions on the market, but unfortunately the same is also true for the number of functionally safe protocols used and the fieldbus itself.


Fieldbus independence has always been a great strength of ASi and ASi Safety. There are gateways for almost all relevant fieldbuses and safety protocols. This makes the system architecture at the I/O level completely independent of the used controller, which means that it can be standardized across all applications.


Needless to say, this advantage also applies to ASi-5 Safety. Just as with the introduction of ASi-5 in the standard area, ASi-5 Safety also offers many new options. The higher data bandwidth and extended diagnostic and parameterization options are ideal for resource-intensive applications. 

This for example, makes the future implementation of IO-Link Safety possible.

ASi-5 Safety has been an integral part of ASi-5 from the very beginning: both use the same communication technology. In the case of ASi-5 Safety modules, only the normatively required protection of the data is added - with an additional checksum.This makes the transmission of these signals functionally safe up to SIL 3/PLe. This is essential whenever standards require such functional safety to protect people and the environment.

Just like ASi-3 Safety at Work, ASi-5 Safety was once again tested and certified externally according to applicable functional safety standards. Similarly, the process used for ASi-5 Safety achieves a performance level up to PLe according to ISO 13849-1, or a safety integrity level up to SIL3 according to IEC 61508/62061.

The topic of cyber security is more relevant than ever. In the industrial sector, the reliability of processes and production in particular is becoming increasingly important.


Like the standard ASi-5 communication, ASi-5 Safety is almost tap-proof due to the nature of the system. The reason:  the data transfer via OFDM with dynamic frequency assignment,makes it very complex to capture the exchanged messages. This requires the entire context of the connection set-up between ASi master and ASi node. Besides, the clock frequencies must be precisely synchronized just like between the ASi master and ASi node according to the ASi-5 protocol.


Cyber security is also enhanced by the fact that the gateway creates a logical break between TCP/IP, ASi-5, and ASi-5 Safety. This means that high safety requirements only need to be placed on the ASi-5 Master, which establishes the connection to TCP/IP. ASi-5 modules, on the other hand, are much less problematic in terms of safety, since they cannot communicate over TCP/IP networks. Those responsible for network security can thus focus on significantly fewer devices and check them more carefully.

Like ASi, ASi-5 Safety is characterized by maximum stability and availability. Defective masters can therefore be replaced easily and without complications: Thanks to the backup in the ASi master, the replacement device is automatically addressed and parameterized just like the original device .

ASi-5 Safety is very flexible: depending on the profile and application scenario, 1 to 64 safe process data along with additional standard  – each bidirectional – can be exchanged with one module. In the process, cycle times of up to 1.27 ms can be achieved for up to 16 safe inputs and 16 safe outputs each. Available diagnostics and acyclic services have no influence on the cycle times.

As an integral part of ASi-5, ASi-5 Safety can transmit safe and standard data simultaneously. Up to 32 bytes are available cyclically for this purpose. The safe data always has a 1-byte checksum, which enables safe communication up to level SIL3/PLe. As with pure ASi-5 standard modules, there is also a diagnostic and an acyclic channel. This also allows ASi-5 Safety modules to transmit detailed diagnostic messages in case of an event. An additional high-performance method is also available to read out additional information if required – e.g., for predictive maintenance or similar applications.

This can save considerable costs in applications with multiple signals. ASi-3 Safety can also be used for modules that have many signals. In this case, however, each safe signal occupies a separate address. Just as with ASi-5, ASi-5 Safety can process much more data per master and thus greatly reduce connection costs – thanks to the significantly higher data bandwidth per address. For example, with the ASi-5 Safety module BWU4210, a total of 2x2-channel safe inputs and an additional 12 I/Os are available under just one ASi-5 address. In contrast, the same amount of data occupies 2 single and 3 A/B addresses with ASi-3.

However, ASi-5 may not always be the most advantageous one. Even with ASi-3 Safety, only one address is occupied for a single E-stop with a 2-channel safe input – and at lower cost. Both technologies will therefore be used in parallel in the future.

Do you have questions about ASi-5 Safety? Or do you need a special product?

We will be happy to inform you about the new Safety Generation. Please also contact us if you need a specific ASi-5 Safety Module or a gateway with ASi-5 Safety Monitor.